1. Field of the Invention
The present invention relates to an apparatus for installing eyeglass lenses. More particularly, the present invention relates to an apparatus for installing eyeglass lenses for rimless eyeglasses mounted with a temple and a bridge.
2. Description of the Prior Art
FIG. 9 shows an example of a conventional eyeglass lens-mounting construction. A pair of eyeglasses 1 includes a lens 2 having a circular through-hole 3 formed near its edge. A temple 5 to be supported by the ear is installed on the lens 2 by means of a connection member 4. A male screw member 6 is provided on the connection member 4. The male screw member 6 is inserted into the through-hole 3 of the lens 2. A nut 7 is screwed on the male screw member 6 to fix the connection member 4 to the lens 2. A supporting piece 8 is provided on the connection member 4. The supporting piece 8 is disposed along the edge of the lens 2. The supporting piece 8 prevents the connection member 4 from rotating on the male screw member 6 and prevents the temple 5 from loosening. The connection member 4 is also formed on a bridge for connecting the two lenses 2 with each other to prevent the lenses 2 from loosening relative to each other.
Conventionally, a temple and a bridge are displayed in a display case or store window, with the temple and the bridge installed on a sample lens that is made of synthetic resin or the like. When a customer selects a temple and a bridge, a lens adjusted to the eyesight of the customer is molded into the same shape as that of the sample lens. Then, through-holes are formed in the lens. Then, a male screw part formed on a connection member of the temple is inserted into one of the through-holes, and a male screw part formed on a connection member of the bridge is inserted into the other through-hole. Then, the connection members are fixed with a nut.
A manufacturer installs the temple and the bridge on the sample lens such that the through-hole is formed at a correct position. That is, the distance between the edge of the sample lens and the through-hole is set to be equal to the distance between the inner side of the supporting piece and the male screw part. Thus, if the though-hole is formed at a position in the lens such that the position is coincident with the through-hole of the sample lens, the supporting piece can be positioned along the edge of the lens. The lens can then be installed securely on the temple and the bridge.
However, it is difficult to form the through-hole at a precise position of the lens such that its position is coincident with the through-hole of the sample lens, unless the through-hole forming task is carried out by a very skilled operator. For example, if the distance between the edge of the lens and the through-hole is too short, a gap is generated between the supporting piece of the connection member and the edge of the lens. As a result, the temple or other element is loosened. If the distance I between the edge of the lens and the through-hole is too long, the supporting piece of the connection member is misaligned relative to the edge of the lens. Consequently, the connection member cannot be installed on the lens. In the latter case, it is necessary to enlarge the through-hole toward the edge of the lens, causing the male screw part to be unstable inside the through-hole and thus, the connection member is loose.